1. Field of the Invention
The present invention generally relates to an illumination system for a projector, and more particularly, to an illumination system for a dual-lamp projector.
2. Description of Related Art
FIG. 1 is a diagram of a conventional dual-lamp illumination system. Referring to FIG. 1, a conventional dual-lamp illumination system 100 includes a first light source 110, a second light source 120, a light-combining component 130, an light integration rod (LIR) 140 and a color wheel 150. The LIR 140 has a light incidence end 142 and a light emitting end 144, the light-combining component 130 is disposed beside the light incidence end 142 of the LIR 140. The light-combining component 130 is located on optical paths of the light beam L10 emitted from the first light source 110 and the light beam L20 emitted from the second light source 120 so as to combine the light beam L10 and the light beam L20. The color wheel 150 is disposed beside the light emitting end 144 of the LIR 140.
After the light beam L10 passes through the light-combining component 130, the light beam L10 enters the LIR 140 from the light incidence end 142 thereof, while the light beam L20 is reflected by the light-combining component 130 and then enters the LIR 140 from the light incidence end 142 thereof. The light beam L10 and the light beam L20 in the LIR 140 would form an illumination beam L30 with substantial uniformity that emits out from the light emitting end 144 thereof and then enters the color wheel 150. The illumination beam L30 is filtered into a light beam with different colors by different portions of the color wheel 150 through which the illumination beam L30 passes.
FIG. 2 is a diagram of the color wheel of FIG. 1. Referring to FIG. 2, the color wheel 150 has a red filter portion 152, a green filter portion 154 and a blue filter portion 156. When the illumination beam L30 passes through the red filter portion 152, it is filtered into a red light beam; when the illumination beam L30 passes through the green filter portion 154, it is filtered into a green light beam; when the illumination beam L30 passes through the blue filter portion 156, it is filtered into a blue light beam.
However, when the illumination beam L30 is incident upon a joining boundary 150a of two adjacent light filter portions, it is incident upon two color filter portions simultaneously so that an non-uniform-color light is produced, which would reduce the display quality of the projector employing the dual-lamp illumination system 100. In addition, although the dual light sources are able to increase the luminance of a frame, but such a design requires an additional a light-combining component 130 to introduce two light beams emitted from the two light sources into the LIR 140, which accordingly increases the weight and the volume of the dual-lamp illumination system 100.